NEC VT440 Service Manual page 67

METHOD OF ADJUSTMENTS
1. Adjustment of the optical axis (Shadow adjustment)
This adjustment is intended to remove color stain (defined as shadow hereafter) that may appear at the edge
part of the projected screen possibly caused by a problem around the optical engine block.
Adjustments can be carried out based on the flow chart in Fig. 1 and the objective blocks to be adjusted, shown
in Fig. 2.
1-1. Tools required
The following tools are required for adjustments:
<Tools to be used>
• Ball driver for FL adjustment and FL2 adjustment : Opposite side 2.0mm
(Ball driver DB-20 (2.0mm), Part No. : 92339583)
• Minus screwdriver for Mirror 1 adjustment: Blade width 5.0mm
<Jig for lamp lighting>
• Dummy load PWB (VT) (Part No.: 98999241)
1-2. Preliminary arrangements before adjustments
1) Remove the top cover Assy.
2) Remove the Main PWB Assy, the LCES or LCEX PWB Assy, and the Key PWB Assy.
3) Remove the Cover (suction air duct) Assy (Part No.: 24FT7461), the Suction air duct (SK) Assy (Part
No.: 24FT7451), and the Optical cover (SK) (Part No.: 24F32021).
Taking out the filter Assy B in advance facilitates the removal of the optical cover (SK).
4) Mount the dummy load and turn on the power source circuit.
5) Zoom the lens to maximum image size.
6) Adjust the focus of the screen overall by means of the lens focus adjuster. This adjustment should be
carried out in the all-white mode.
1-3. Method of shadow adjustment in each color
1
1-3-1. Vertical shadow adjustment for G and R (when the shadow color is magenta, cyan, or blue)
Replace the FL vertical adjusting screw. (Part name: Nylock screw (HLSS4*6), Part No.:
24N04751)
2
Then, follow the working procedures below by the use of a ball driver (opposite side 2.0mm).
Sufficiently loosen the FL vertical fixing screws (Part name: special screw (PL-HM2.5*6), Part
3
No.: 12851741) (in 2 positions).
Loosen the FL horizontal fixing screws by one turn (Part name: special screw (PL-HM2.5*6),
4
Part No.: 12851741) (in 2 positions).
Turn the FL vertical adjusting screw to eliminate the vertical shadow (magenta, cyan, and blue)
5
from the projected screen.
Fix the FL horizontal fixing screws (in 2 positions).
The fixing torque is 3.5 ± 0.5kgf·cm.
6
Fix the FL vertical fixing screws (in 2 positions).
The fixing torque is 3.5 ± 0.5kgf·cm.
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